PROJECT ABSTRACT/SUMMARY Treatment advances have led to a rapidly growing population of adolescent and young adult (ages 15 to 29) survivors of childhood cancer (AYA) aging into adulthood and adult healthcare. Despite cure, AYA remain physically and psychologically vulnerable as the toxicity of treatment takes its toll. Survivorship self- management includes life-long follow-up care, health promotion, disease surveillance, and management of late effects. This is especially difficult for AYA, an understudied and underserved group facing health disparities and unmet needs. Survivorship care plans (SCPs) are documents to inform survivors and providers of long- term needs for follow-up and management of health and to improve communication among providers. SCPs are widely-used in adult oncology and are increasingly viewed as a prerequisite to optimal AYA survivor self- management and collaborative, continuous care across pediatric and adult medical settings. However, no study to date has established best practices for implementation of SCPs with AYA. Objectives: The proposed study involves a formative, mixed methods evaluation of AYA SCP implementation that is informed by implementation science methods and theory. It capitalizes on an extant study whereby all AYA as part of a self-management intervention will receive an individualized SCP. The SCP will also be given to their oncology and primary care providers, and asked to be shared with a parent or support person. This extant study will not inform barriers or facilitators of SCP implementation, which is critical information for the long-term goal of incorporating SCPs into standard of care. The proposed study aims to fill this knowledge gap. Methods: A sequential exploratory mixed methods design will be used to integrate qualitative and quantitative data to determine stakeholder perceptions about SCP implementation and formulate generalizable recommendations for future SCP implementation. In Aim 1, interviews will elicit qualitative data about SCPs from 12 AYA survivors who participated in the extant trial (SCP-only group) and their parent/support person and providers. In Aim 2, a newly created survey based on qualitative results will further assess barriers and facilitators of an expanded sample of 40-50 stakeholders from each group. Providers will also complete measures of attitudes related to implementation climate and SCPs. In Aim 3, we will summarize and integrate qualitative and quantitative data regarding barriers and facilitators, including attitudes of the medical providers, across stakeholders using mixed methods informational matrices and provide recommendations for future SCP implementation. Relevance: This study is consistent with the NCI?s priority to improve long-term outcomes by funding implementation science and survivorship research, PA-16-011, and the federal call for wide-spread implementation and evaluation of SCPs. It fills a critical knowledge gap by rigorously evaluating perceptions about AYA SCP implementation within and across multiple stakeholders. Results will inform a future multisite implementation study that will definitively test the scale-up of AYA SCPs.